There are many materials that exist in nature, or are synthesized, that have low stability under ambient conditions. These materials may decompose, disassociate, lose viability, etc. through reaction with oxygen present in the atmosphere, or losing essential components by volatilization at ambient and elevated temperatures. Examples include flavors, flavor compounds, aromas, fragrances, vitamins, nutrients (such as omega 3 oils, carotenoids, vitamin A and E), alcohols, acetones, ketones, aldehydes, organic acids, antioxidants, biologically active substances etc., hereinafter referred to as sensitive materials.
Sensitive materials may have single or multiple components that can be categorized based on their level of volatility. Components that reach the boiling point at low temperatures are categorized as having high volatility, high notes or top notes. An example of a low boiling point component is diacetyl (2,3-Butanedione) with a boiling point of 88.degree. F. (water has a boiling point of 212.degree. F.) Diacetyl is used to bring the characteristic dairy flavor in butter, coffee, and vinegar.
Volatile materials may comprise a single low boiling point component or may comprise a mixture of low, medium and/or high boiling components. The medium and low notes are not volatile at ambient or elevated temperatures (250.degree. F. and above), and are therefore generally unaffected by atmospheric conditions or elevated processing temperatures. Loss of the high notes in volatile materials very often results in a finished product that is out of balance.
The high notes of volatile materials are the most sensitive portions of the product. High notes can be lost through volatilization which is accelerated at temperature above 40.degree. F. Loss of high notes can also occur during storage, incorporation in a food product, processing of a food product, and storage of that food product even under frozen conditions.
There have been attempts to overcome the problems associated with maintaining high notes in a formulation. For instance, over formulation is used to supply the high notes (high volatiles) in greater quantities to compensate for the losses. However, this solution does not address the relative concentrations of differing volatile compounds in the original product versus the resulting product. Furthermore, it is difficult to anticipate how much of the high notes will be lost. In addition, high notes are lost over a period time and the amount of loss can depend on temperature, so that the composition of the volatile material is constantly changing.
Another approach to delivering a balanced composition of high, medium, and low notes has been through encapsulation technology. Early attempts used spray drying and spray chilling technologies to stabilize the flavor and fragrance compositions. With spray drying, a volatile substance is first emulsified in an aqueous solution of a water-soluble protective colloid, such as gelatin, and carbohydrates (e.g. gum arabic, starch, dextrin. The emulsion is then sprayed into a column of heated air or gases to evaporate the water. The resulting dry particles have a water-soluble shell or capsule of the water-soluble colloid in which the volatile substance, such as a flavor, is embedded or encapsulated in the form of minute droplets. Spray chilling is differentiated from spray drying by having the emulsion being sprayed into a column of ambient or chilled air.
U.S. Pat. No. 3,857,964 teaches controlled release flavor compositions which comprise flavor particles having an outer coating of a physiologically inert, water-softenable and swellable material. Flavor particles may be formed by adding and stirring volatile agents, such as cyclic acetal compounds, into a polymeric material. The resulting flavor particles are then coated by stirring them into a sodium alginate solution, passing them through a size-limiting orifice into a room temperature bath of calcium lactate solution.
U.S. Pat. No. 5,607,708 relates to an encapsulated flavoring material formed of an edible, oil-insoluble, water-soluble outer shell surrounding an edible, water-insoluble inner core that is liquid at a temperature of about 45.degree. C. and contains a volatile, oil-soluble flavoring material dissolved or dispersed in the inner core. Materials suitable for the outer shell include gelatin, water soluble gums, starches or dextrins. The cover material may be an unsaturated vegetable oil, fat and/or partially hydrogenated oil or fat. It is important during the manufacture of the core materials that the material have a relatively low melting point so that the volatile components may be mixed with this material at low temperatures, thereby minimizing the loss of the volatile component. Coannular centrifugal extrusion methods may be used to form particles of the core material and simultaneously to coat them with the shell material. Coannular extrusion means are used in U.S. Pat. No. 5,399,368 to produce coated materials in which volatile materials, such as coffee oil, are entrained.
U.S. Pat. No. 5,874,102 teaches encapsulated fatty acid salt products comprising a core material coated with continuous film that serves as a barrier to volatile compounds contained in the core matrix. The particles may then be coated by direct spraying means. Direct spraying of a volatile-containing core material by an aqueous solution of first and second coagulating agents is also shown in U.S. Pat. No. 5,558,889. U.S. Pat. No. 5,004,595 teaches the production of similar coated particles using a fluidized bed process.
U.S. Pat. No. 4,689,235 discloses an encapsulating matrix composition that is extrudable at a pressure in the range of 1 to 10 atm and having an improved loading capacity up to 40% comprising maltodextrin and hydrogen octenylbutanedioate amylodextrin. The matrix may contain from 5 to 40 wt. % of a normally liquid or volatile active ingredient which is added in a tank having heating and agitating means.
U.S. Pat. No. 4,576,826 relates to a method for producing flavorant capsules by forming a stable emulsion of an edible oil and an aqueous essence. The emulsion is directly sprayed or dropped in a dropwise manner onto an agitated powdered edible protein, carbohydrate or mixture thereof to form capsule shells thereon. Frozen essences may be utilized in the form of frozen particles which are added to the coating material prior to curing.
While spray drying and spray chilling were able to transform a liquid flavor into a solid particle, they also had inherent limitations such as the use of large volumes of air. Compounds sensitive to oxygen in air will begin to oxidize and decompose. For example, materials with multiple double bonds such as conjugated linoleic acid, omega 3 oils, fish oils, as well as anaerobes and facultative anaerobes such as, but not limited to, Bifidobacterium sp., and Lactobacillus sp., will lose potency or activity after exposure to oxygen. Additionally, heat is involved in both processes that will cause almost complete volatilization and/or oxidation of the low boilers or sensitive materials even with over formulation.